Today, the World Health Organisation defines health as ‘a state of complete physical, mental and social well-being and not merely the absence of disease of infirmity’
(http://www.who.int/about/definition/en/print.html). However, health is a holistic concept that encompasses many aspects including not only factors such as disease and nutrition, but also how a person is able to function daily, their overall quality of life and even their own self perception of health (Noack 1987; Freund et al.2003; Duncan 2007; Huber et al. 2011; Brüssow 2013; Reitsema and McIlvaine 2014: 181). Therefore, rather than being considered in static binary opposition to disease, “health” reflects a changing continuum (Goodman et al. 1988:
21 Figure 2.1: Seyle’s (1973) general adaptation model (Bush 1991: 21)
195; Bush 1991: 11; Larsen 2015: 9). Furthermore, how “health” is perceived within a population is subject to cultural and temporal change, with past perceptions of what is considered “healthy” potentially diverging from our own (Goodman et al. 1988; Freund et al. 2003: 4-6; King 2005; Roberts 2009: 154; papers within Agarwal and Glencross 2011; Temple and Goodman 2014). While the multifaceted and complex nature of health can be examined in living populations through a multitude of clinical data, biocultural investigations of health are limited to the data that can be obtained from skeletal remains (DeWitte and Stojanowski 2015).
A key concept within biocultural studies of health in the past is the identification of stress. Within physical anthropology, stress is defined as ‘a physiological changed caused by strain on an organism from environmental, nutritional and other pressures’ (Reitsema and McIlvaine 2014: 181). One of the most influential concepts of stress within biocultural studies is Seyle’s (1973) general-adaptation-syndrome (GAS) model (Figure 2.1). Within it, stress is considered as ‘the non-specific response of the body to any demand upon it’ (Seyle 1973: 692). The GAS model identifies three key stages of response in the body (Figure 2.1). In the first stage, or ‘alarm response’, initial exposure to a stressor leads to an excessive response due to an individual’s low resistance (Seyle 1973: 694). If this initial exposure is severe enough, it may overwhelm the individual and lead to death (Seyle 1973: 694). With repeated exposure the ‘resistance stage’ is reached, where an individual’s resistance to a particular stressor increases as the body adapts to accommodate it (Seyle 1973: 695). However, if the individual is subject
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Figure 2.2: Goodman and Armelagos (1989: 226) stress adaptation model (revised from Goodman et al. 1984a)
to long-term, continued exposure to the stressor, it will reach a point of exhaustion, or ‘collapse’, where it is no longer able to adapt, rendering it more susceptible to other stressors and eventually leading to death (Seyle 1973: 696). Ultimately, it is the ability of the body to recover, adapt and maintain homeostasis that determines the health of the individual, and the population overall (Seyle 1973). This Seylean notion of stress has been criticised for its explicit focus on physiological aspects of stress and its failure to consider psychological stress
(Goodman et al. 1988: 174-175; Armelagos and Goodman 1991; Bush 1991; Weston 2012: 504-505). Bush (1991: 15) in particular argues that the way a person perceives social and environmental constraints will also influence the way in which they experience stress. Therefore, she argues that there is no “universal stressor” as individuals will experience and respond to stress differently, something she terms the ‘individuality of response’ (Bush 1991: 17).
The level of stress a population is exposed to and its ability to adapt is highly dependent on the complex interaction of environmental, cultural, and biological constraints and adaptations. Goodman et al.’s (1984; 1988) model for the interpretation of stress in skeletal populations, which has become the primary reference of biocultural stress studies, identifies the potential of the environment to both buffer and create stress (Figure 2.2).While cultural adaptations can be made to mitigate these stresses, for example through technological advancements or through the organisation of social systems, these changes can also be a source of additional stressors (Goodman et al. 1984a). For instance, a population may choose to preferentially protect or expose different sections of its society to stress. If cultural adaptations fail to buffer these stresses, an individual’s host response, affected by factors such as their genetic,
developmental and physiological status, becomes important (Goodman et al. 1984a). For example, the youngest and oldest members of a society are often the most vulnerable to
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stress (Goodman and Armelagos 1989; Overfield 1995; Rogers 1997; Lewis 2002: 38; Last and McGinnis 2003: 47; WHO 2008: 8-10; Lupien et al. 2009), and studies have shown females tend to be more physiologically buffered from stress than males (Stinson 1985; Overfield 1995: 170- 182; Ortner 1998; Last and McGinnis 2003: 47; Lee and Owens 2007: 133). If a population’s cultural and individual adaptation to stress ultimately fails, physiological disruption, poor health and eventually death may occur (Temple and Goodman 2014: 188).
In living populations, the identification of stress and physiological disruption can be achieved through the physical examination of a living patient’s symptoms and hormone levels. However, within palaeopathology, evidence for stress must be derived indirectly from a series of
recognised diagnostic dental and skeletal lesions, commonly referred to as “stress markers” or “stress indicators” (Goodman et al. 1984a; 1988; Lewis and Roberts 1997; Goodman and Martin 2002; Reitsema and McIlvaine 2014; Larsen 2015: 8-58). These stress markers either represent physiological growth disruptions (e.g. enamel hypoplasia, Harris lines, growth and stature), metabolic disturbances (i.e. cribra orbitalia, porotic hyperostosis, and vitamin C and vitamin D deficiency), infection or trauma. Understanding the specific cause of an individual stress indicator is often not possible, due to its non-specific nature and the wide range of stressors that have been implicated in their aetiology (Cutress and Suckling 1982; Goodman et
al. 1984a; 1988; Lewis and Roberts 1997; Temple and Goodman 2014; Vercellotti et al. 2014).
They include, amongst others: nutritional deficiency, disease, parasitic infection, poor living conditions, and psychological disturbance (Goodman et al. 1984a; 1988; Martin et al. 1985; Stuart-Macadam 1985; 1991; Bush 1991; Lewis and Roberts 1997; Klaus 2014; Tanner and TAPS Bolivia Study Team 2014). This situation is further exacerbated by the potential co- existence of multiple stressors (Goodman et al. 1988: 187). For example, malnutrition often increases an individual’s susceptibility to infection, as well as producing metabolic disturbances implicated in anaemia and vitamin C deficiency (Scrimshaw and SanGiovanni 1997; Buckley 2000: 499; Jacob and Sotoudeh 2002; Scrimshaw 2003). Stress markers are then best considered as non-specific indicators of stress (Goodman 1993; Lewis and Roberts 1997; Goodman and Martin 2002).
An important consideration that must be made is that the identification of stress indicators within a population cannot be directly linked to health status. While the physiological disruptions responsible for the manifestation of stress indicators are “unhealthy”, stress indicators represent a physiological disruption at a specific point in time (Reitsema and McIlvaine 2014: 155). Therefore, they cannot be considered as a direct measure of overall health outcomes or broader perceptions of well being (Temple and Goodman 2014: 189-190).
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Instead, they should be used to evaluate stress and adaptation within a population in light of environmental, sociocultural and biological constraints within the community. Goodman et al (1988) emphasise the importance of following a holistic approach that utilises multiple stress indicators to understand the total stress load at the population level.
Following this approach, distributions of stress indicators amongst different societies have been used to assess the effect of cultural and environmental factors. Two examples of areas where this has been successfully applied is the study of health implications of the transition to agriculture (Cohen and Armelagos 1984; Kent 1987; Armelagos 1990; Larsen 1997; Starling and Stock 2007; Eshed et al. 2010), and the impact of urbanisation (Brothwell 1994; Lewis 2002; Sullivan 2005; Brickley et al. 2007; Redfern 2007; Redfern and DeWitte 2011a). Intra-
population studies of the differential health experiences of different social identities, such as age, gender and status have also been undertaken (Šlaus 2000; Robb et al. 2001; Redfern 2005; Gowland and Redfern 2010; DeWitte 2014).